Resonance inspection is a proven non-destructive method for the evaluation of stiff components. Resonance inspection may be provided by impulse-induced vibration, swept-sine wave stimulation, and other acoustic or ultrasonic techniques in which a part under test is vibrated and the vibrational response of the part is measured. Resonance measurements may be made with electronic listening devices, contact transducers, laser interferometers, and other contact and non-contact means. Resonance data may be processed via fast Fourier Transforms (FFT), direct waveform measure, or other methods. Resonance inspection can provide quantifiable results from non-destructive test means that may be used to evaluate parts.
Part resonances are determined by the part's material properties, stiffness, and dimensions, all of which are typically tightly tied to a part's ability to perform as designed. When these material or geometric features are changed in a manner that will affect part performance, due to manufacturing defects or in-service damage, the resonances will reflect these changes, and the part can be discriminated from the acceptable population based on the resonance response of a part under test.